Intervertebral distractor and implant insertion instrument

ABSTRACT

A distractor/guide sleeve assembly is provided which includes a body having a cylindrical throughbore and a distractor assembly mounted thereon. The distractor assembly includes a rotatable dial, a pair of distractor rods, and two pairs of jaws. A plate is secured to the distal end of each distractor rod. Each plate includes a plurality of cam members which are slidably positioned in cam slots formed in the jaws of each of the pairs of jaws. The dial is operably connected to the jaws via the distractor rods such that rotation of the dial effects movement of the pairs of jaws between approximated and distracted positions. An insertion tool is also provided which includes a handle and distal engaging structure for releasably engaging an implant. The engaging structure includes a pair of prongs or protrusions having a slip resistant outer surface. The prongs are configured to be releasably received within correspondingly shaped bores formed in an implant.

[0001] This application is a Divisional application of U.S. applicationSer. No. 09/850,494 filed May 7, 2001 and claims priority fromProvisional Application Serial No. 60/202,225 filed May 5, 2000 and ishereby incorporated by reference.

BACKGROUND

[0002] 1. Technical Field

[0003] The present disclosure relates generally to instrumentation forinserting an implant into a body receiving bed. More particularly, thepresent disclosure relates to instrumentation for guiding andpositioning a dowel into a receiving bed formed in an intervertebralspace.

[0004] 2. Background to Related Art

[0005] Distractors and guide sleeves for positioning an implant into areceiving bed in the intervertebral space are well known. Thesedistractors include forceps type distractors as well as wedge typedistractors which are pushed into the intervertebral space and distractupon insertion. The guide sleeve typically includes a cylindrical sleevewhich is mounted to the adjacent vertebrae such that the instruments andimplant can be positioned in the intervertebral space through thecylindrical sleeve. At least with respect to wedge type distractors,distraction of the vertebrae occurs unevenly with the front face of thevertebrae being distracted first. This is not desirable.

[0006] Accordingly, a need exists for an improved distractor/guidesleeve assembly which includes a simple integral assembly and providesfor uniform distraction of adjacent vertebrae. A need also exists for aninsertion tool useable with the distractor/guide sleeve assembly forinserting an implant into the intervertebral space.

SUMMARY

[0007] In accordance with the present disclosure, a distractor/guidesleeve assembly is provided which includes a body having a cylindricalthroughbore and a distractor assembly mounted thereon. The distractorassembly includes a rotatable dial, a pair of distractor rods, and twopairs of jaws. A plate is secured to the distal end of each distractorrod. Each plate includes a plurality of cam members which are slidablypositioned in cam slots formed in the jaws of each of the pairs of jaws.The dial is operably connected to the distractor rods such that rotationof the dial effects axial movement of the distractor rods. Axialmovement of the distractor rods cause corresponding movement of each ofthe plates to move the cam members within the cam slots formed in eachof the jaws. Movement of the cam members within the cam slots effectsmovement of each of the pairs of jaws between approximated anddistracted positions.

[0008] An insertion tool is also provided which includes a handle anddistal engaging structure for releasably engaging an implant. Theengaging structure includes a pair of prongs or protrusions having aslip resistant outer surface. The prongs are configured to be releasablyreceived within correspondingly shaped bores formed in an implant.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various preferred embodiments of the presently discloseddistractor/guide sleeve assembly are described herein with reference tothe drawings, wherein:

[0010]FIG. 1 is a perspective view of one preferred embodiment of thepresently disclosed distractor/guide sleeve assembly;

[0011]FIG. 1A is a perspective view with parts separated of thedistractor/guide sleeve assembly shown in FIG. 1;

[0012]FIG. 2 is a side view of the distractor/guide sleeve assemblyshown in FIG. 1;

[0013]FIG. 2A is a front view of the distractor/guide sleeve assemblyshown in FIG. 1;

[0014]FIG. 3A is a top view of the ring of the distractor/guide sleeveassembly shown in FIG. 1;

[0015]FIG. 3B is a side cross-sectional view of the ring shown in FIG.3A taken along section lines 3B-3B in FIG. 3A;

[0016]FIG. 3C is a top view of the dial of the distractor/guide sleeveassembly shown in FIG. 1;

[0017]FIG. 3D is a side cross-sectional view of the dial shown in FIG.3C taken along section lines 3D-3D in FIG. 3C;

[0018]FIG. 4 is a side view of the distractor rod of thedistractor/guide sleeve assembly shown in FIG. 1;

[0019]FIG. 4A is a side cross-sectional view of the distractor rod shownin FIG. 4;

[0020]FIG. 5 is side view of one plate portion of the distractor/guidesleeve assembly shown in FIG. 1;

[0021]FIG. 5A is a top view of the plate portion shown in FIG. 5;

[0022]FIG. 6 is a side view of one jaw of the distractor/guide sleeveassembly shown in FIG. 1;

[0023]FIG. 6A is a front view of the jaw shown in FIG. 6;

[0024]FIG. 7 is a front view of one cover plate of the distractor/guidesleeve assembly shown in FIG. 1;

[0025]FIG. 7A is a side view of the cover plate shown in FIG. 7;

[0026]FIG. 8 is a front view of one preferred embodiment of thepresently disclosed implant insertion tool;

[0027]FIG. 9 is a front view of the distal end of the insertion toolshown in FIG. 8;

[0028]FIG. 10 is a side view of one preferred embodiment of thepresently disclosed implant; and

[0029]FIG. 11 is a side cross-sectional view of the implant shown inFIG. 10 taken along section lines 11-11 in FIG. 10

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] Preferred embodiments of the presently disclosed distractor/guidesleeve assembly will now be described in detail with reference to thedrawings in which like reference numerals designate identical orcorresponding elements in each of the several views.

[0031]FIGS. 1 and 1A illustrate perspective views of the presentlydisclosed distractor/guide sleeve assembly, which is shown generally as10. Distractor/guide sleeve assembly 10 includes a body 12, a rotatabledial 14, a ring 16, a pair of distractor rods 18, two pairs of jaws 20 aand 20 b and a pair of cover plates 22 a and 22 b. As will be describedin greater detail below, dial 14 is rotatable to retract or advancedistractor rods 18 to effect opening and closing, i.e., of each pair ofjaws 20 a and 20 b.

[0032] Referring to FIGS. 2 and 2A, distractor body 12 includes atubular portion 24 and a hollow rectangular base portion 26 which areintegrally formed. Although not shown, windows or openings may be formedin tubular portion 24 or base portion 26 to provide visibility. Tubularportion 24 defines a lumen 28 (FIG. 1) having a first open end 28 a anda second end 28 b in communication with hollow base portion 26. Asemi-circular rod guide 30 is formed on each side of tubular portion 24.Rod guides 30 are configured to slidably receive and guide distractorrods 18. First end 28 a of tubular portion 24 includes a series ofthreads 32 for rotatably receiving dial 14.

[0033] Referring to FIGS. 3a and 3 b, ring 16 is circular and includes apair of stepped bores 34 and an annular channel 36 formed thereabout.Stepped bores 34 are dimensioned to receive screws 38 (FIG. 1A) forsecuring rods 18 to ring 16. Ring 16 is secured within dial 14 (seeFIGS. 3c and 3 d) with pins 40 (FIG. 1A). Pins 40 extend throughopenings 42 in dial 14 into annular channel 36 of ring 16 to secure ring16 within dial 14 while allowing dial 14 to rotate in relation to ring16. Dial 14 includes a grooved outer surface 15 to facilitate grippingand rotating dial 14. Dial 14 also includes a threaded bore 17dimensioned to receive threaded first end 28 a of body 12.

[0034] Referring to FIGS. 4, 4A, 5 and 5A, each distractor rod 18includes a rod portion 44 and a plate portion 46. Rod portion 44includes a first end having a threaded bore 48 and a second end having aslot 50 formed therein. Each threaded bore 48 is dimensioned to receivescrew 38 (FIG. 1A) to secure the first end of rod portion 44 to ring 16.Each slot 50 of rod portion 44 is configured and dimensioned to slidablyreceive plate portion 46. Plate portion 46 is frictionally retainedwithin slot 50. Alternately, other retaining means may be used to secureplate portion 46 within slot 50, e.g., screws, adhesives, ultrasonicwelding, etc.

[0035] Plate portion 46 includes a paddle section 52 and a handlesection 54. Handle section 54 is dimensioned to be received in slot 50of rod portion 44. Paddle section 52 includes a flat base 51 having aplurality of cam members 56 extending therefrom. Cam members 56 will bedescribed in further detail below.

[0036] Referring to FIGS. 6 and 6A, each jaw 20 of the two pair of jaws20 a and 20 b includes a body 60 having a distally extending finger 62.Body 60 includes one or more cam slots 64 formed therein. Preferablybody 60 includes two cam slots, although three or more may be provided.Alternately, only a single cam slot need be provided. Cam slots 64 aredimensioned to receive cam members 56 formed on plate portion 46 ofdistractor rods 18. Alternately, only a single pair of jaws need beprovided on the distractor/guide sleeve. Such an embodiment would alsorequire only a single distractor rod and cover plate.

[0037] Referring to FIGS. 7 and 7A cover plates 22 a and 22 b aresecured to open sides of base portion 26 to retain jaws 20 and plateportion 46 of distractor rods 18 in engagement. Cover plates 22 a and 22b may snap fit to base portion 26 or other attachment means may beprovided, e.g., screws, welding, adhesives, etc.

[0038] In operation, when dial 14 is rotated in a clockwise direction onthe threaded end of body 12, dial 14 advances ring 16 towards the secondend of body 12. Movement of ring 16 advances distractor rods 18 in adirection parallel to the longitudinal axis of body 12, thus advancingcam members 56 in a direction parallel to the longitudinal axis of body12. As cam members 56 move in relation to cam slots 64, each jaw 20 ofeach pair of jaws 20 a and 20 b is urged outward away from thelongitudinal axis of body 12 to increase the spacing between the fingers62 of each pair of jaws 20 a and 20 b. When dial 14 is rotated in acounter-clockwise direction, rods 18 are retracted to decrease thespacing between each of fingers 62 of each pair of jaws 20 a and 20 b ina manner similar to that described above.

[0039] The above described distractor/guide sleeve may be used todistract adjacent vertebrae during spinal surgery, e.g., a cervicalspinal fusion procedure. The distractor body including the tubularportion and the base portion function as a guide for the surgicalinstruments used during the surgical procedure, e.g., reamers, taps,insertion tool, etc. Once the guide sleeve has been parked in theintervertebral space, with fingers 62 positioned between adjacentvertebrae, dial 14 can be rotated to distract the adjacent vertebrae. Itis no longer necessary to relocate the proper graft bed after each timea surgical instrument is used, since the distractor/guide sleeve issecured in a fixed location with respect to the graft bed during theentire procedure. Moreover, the presently disclosed jaw structureprovides a sturdy structure which minimizes wobbling which may occurwhile using the surgical instruments.

[0040]FIGS. 8 and 9 illustrate an insertion tool, shown generally as100, for inserting a thread implant into an implant receiving bed.Insertion tool 10 includes a handle 110, an elongated shaft 111 and animplant engaging structure 120. Implant engaging structure 120 issecured to or formed integrally with elongated shaft 111 and includes abase member 112 and a pair of protrusions or prongs 114. Base member 112includes a flat face which abuts the trailing end of an implant when theimplant is supported on the insertion tool. Protrusions 114 have anouter surface 116 which is at least partially roughened. The roughenedsurface may include ridges, knurling, dimples or any other slipresistant surface.

[0041]FIGS. 10 and 11 illustrate an implant 200 having a cylindricalthreaded body 210 and top and bottom surfaces 212 and 214. Implant 200is constructed from a biocompatible material. Preferably, implant 200 isformed from cortical or cancellous bone. Top surface 212 includes a pairof substantially cylindrical bores 216 formed therein. Bores 216 arepositioned to receive protrusions 114 (FIG. 9) and have an insidediameter substantially equal to the outside diameter of protrusions 114.When protrusions 114 are pressed into bores 216, roughened outer surface116 of protrusions 114 prevent implant 200 from separating from engagingstructure 120 without applying additional force to implant 200.

[0042] In use, after implant 200 has been positioned on engagingstructure 120 of insertion tool 100, handle 110 can be manipulated tothread implant 200 into a previously prepared receiving bed, e.g., atapped bore formed between adjacent vertebrae during a spinal fusionsurgical procedure. Thereafter, insertion tool 100 can be pulledrearwardly with a force sufficient to overcome the frictional engagementbetween protrusions 114 and bores 26 to separate the implant from theinsertion tool.

[0043] It will be understood that various modifications may be made tothe embodiments disclosed herein. For example, any materials having therequisite strength requirements which are suitable for surgical use maybe used to construct the distractor/guide sleeve assembly and insertiontool including surgical grade stainless steel, plastics, etc. Moreover,the size of the distractor/guide sleeve may be changed to suit aparticular surgical procedure, e.g., cervical spinal fusion, lumbarspinal fusion, thoracic spinal fusion, etc. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of thisdisclosure.

1. An implant insertion tool comprising a handle, an elongated shaftdefining a longitudinal axis and a head portion, the head portionincluding a pair of prongs, each prong extending in a directionsubstantially parallel to the longitudinal axis of the elongated shaft.2. An implant insertion tool according to claim 1, wherein each of theprongs include a slip resistant surface.
 3. An implant insertion toolaccording to claim 2, wherein the slip resistant surface includes aplurality of ridges.
 4. An implant insertion tool according to claim 3,wherein each of the prongs is secured to a base member supported on thedistal end of the elongated shaft, the base member having a faceconfigured to abut against one end of an implant.